clk: scpi: error when clock fails to register

Current implementation of scpi_clk_add just print a warning when clock
fails to register but then keep going as if nothing happened. The
provider is then registered with bogus data.

This may latter lead to an Oops in __clk_create_clk when
hlist_add_head(&clk->clks_node, &hw->core->clks) is called.

This patch fixes the issue and errors if a clock fails to register.

Fixes: cd52c2a4 ("clk: add support for clocks provided by SCP(System Control Processor)")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>